They are startled by loud knocking at the castle door - announcing the fateful arrival of an eccentric, emaciated old alchemist, a "mad scientist" named Dr. Septimus Pretorius (Ernest Thesiger) who was formally one of Henry's teachers. A shadow moves across the stranger's face at the door as he introduces his purpose to Minnie: "Tell him ("young Baron Frankenstein") that Dr. Pretorious is here on a secret matter of grave importance and must see him alone, tonight." The gaunt, sinister man with an opera cape is led up to Henry's bedroom through dark corridors (where fireplace flames cause rippling shadow effects). Minnie describes the visitor's mission: "He's a very queer-looking old gentleman, sir, and must see you on a secret, grave matter, he said, tonight, alone." Behind him, a dark, enormous shadow follows as he intrudes into the bedroom - more wavy shadows cast from the room's fireplace ripple across his figure. Professor Pretorius was a Doctor of Philosophy at Henry's university but was booted out. "Booted, my dear Baron, is the word for knowing too much."

Pretorius asks that Elizabeth excuse herself from their private discussion: "My business with you Baron, is private." [There is a sexual ambiguity to Pretorius' character and suggestions of homosexuality. Pretorius' arrival once more threatens to postpone Henry's nuptials.] He turns toward Elizabeth and sneers contemptuously, with his nose proudly turned up. After she exits, Pretorius approaches Henry with an offer:

Pretorius: We must work together.
Henry: (leaping out of bed and protesting) Never! This is outrageous. I'm through with it. I'll have no more of this hell-spawn! As soon as I'm well, I'm to be married and I'm going away.

Henry is upset and agitated by the proposal and unwilling to comply, and he walks away from Pretorius while wringing his hands. Suddenly, he stops - positioned in front of a window where a web-like pattern of shadows criss-cross behind him. With a black-cloaked and white-collared Pretorius at his side, Henry is asked to reconsider his abrupt refusal, visit the doctor's laboratory, and collaborate on a second creation that will better his blasphemous achievements in creating life:

Pretorius: I must beg you to reconsider. You know, do you not, that it is you, really, who are responsible for all those murders? (Henry turns) There are penalties to pay for killing people. And with your creature still at large in the countryside...
Henry: Are you threatening me?
Pretorius: ...I had ventured a hope that you and I together, no longer as master and pupil but as fellow scientists, might probe the mysteries of life and death.
Henry: Never! No further!
Pretorius: And reach a goal undreamed of by scientists...You and I have gone too far to stop, nor can it be stopped so easily. I also continue with my experiments. That is why I am here tonight. You must see my creation!
Henry (curiously): Have you also succeeded, bringing life to the dead?
Pretorius: If you, Herr Baron, will do me the honor of visiting my humble abode, I think you will be interested in what I have to show you. (boasting) After twenty years of secret scientific research and countless failures, I also have created life as we say: 'In God's own image.'
Henry (eagerly): I must know. When can I see it?
Pretorius: I thought you might change your mind. Why not tonight?

They are driven by coach to Dr. Pretorius' lodgings, where they first drink to their new "partnership" as monster-makers. With genteel manners, the macabre scientist, now wearing a black yarmulke-like skull cap, pours their drinks and civilly confesses:

Do you like Gin? - It is my only weakness.

With bright excitement as his eyes widen, the demented, mad scientist (who resembles Mephistopheles) toasts their loony experiments, makes a devilish grin and half-laughs while referring to his own god-like powers:

To a new World of Gods and Monsters. Ha, ha. The creation of life is enthralling, distinctly enthralling, is it not?

[63 years later, a film about James Whale, The Bride of Frankenstein's director, was titled Gods and Monsters (1998).] The skeletal-faced Pretorius hauls a heavy, coffin-like box into the room, removes its cover, and begins placing black cloth-covered, bell-jar containers on a table, explaining:

My experiments did not turn out quite like yours Henry. But Science, like love, has her little surprises - as you shall see.

Pretorius unveils for Henry the results of his experiments with creating life - several miniature homunculi - six small figures (that he has grown from seeds) in glass jars or bottles. The chirping, squeaking, and costumed Lilliputian-like characters include:

• a Queen (Joan Woodbury) - Anne Boleyn
• a lecherous King (Arthur S. Byron) who chews on a turkey drumstick
• a finger-wagging, lecturing Archbishop (Norman Ainsley) who criticizes the amorousness of the King
• and a Mephistophelian Devil (Peter Shaw)

[The King is a perfect double for Henry VIII, looking strikingly like Elsa Lanchester's husband Charles Laughton who played the title character in The Private Life of Henry VIII (1933) and also appeared in James Whale's horror classic The Old Dark House (1932)].

There is a pleasing variety about my exhibits. My first experiment was so lovely that we made her a Queen. Charming, don't you think? Then of course, we had to have a King. Now, he's so madly in love with her that we have to seal him in...My next production looked so disapprovingly at the other two that they made him an Archbishop...the next one is the very Devil - very bizarre, this little chap. There's a certain resemblance to me, don't you think? Or do I flatter myself? I took a great deal of pains with him. Sometimes I have wondered whether life wouldn't be much more amusing if we were all devils, and no nonsense about angels and being good.

Acting out their roles precisely, the King escapes from the top of his bell-jar, madly throws kisses toward the Queen, and runs over toward her flask, while the diminutive Archbishop sternly admonishes and chastises him. Pretorius remarks critically: "Even royal amours are a nuisance." The King is picked up by tweezers and deposited back in his jar.

The last miniature creations include:

• Ballerina (Kansas DeForrest), pirouetting in a tutu
• Mermaid (Josephine McKim), underwater
• [A seventh tiny figure, a Baby (midget actor Billy Barty) appears in a jar on the table. Its introduction was excised from the film between its preview and general release.]

The figures are perfect in shape, but lack size. Pretorius' major challenge was achieving human-size for his creatures while using a "natural" approach, as opposed to Henry's "dead" approach involving grave digging. The devilish doctor wishes to collaborate with Henry to help solve his difficult problem of achieving size:

Pretorius: My little Ballerina is charming but such a bore! She won't dance to anything but Mendelsohnn's Spring Song and it gets so monotonous. My next is very conventional, I'm afraid. But you can never tell how these things will turn out. It was an experiment with seaweed. Normal size has been my difficulty. (To Henry) You did achieve size. I need to work that out with you.
Henry: (disturbed) But this isn't science! It's more like black magic.
Pretorius: You think I'm mad. Perhaps I am. But listen Henry Frankenstein. While you were digging in your graves, piecing together dead tissues, I, my dear pupil, went for my material to the source of life. I grew my creatures like cultures; grew them, as Nature does - from seed. But still, you did achieve results that I have missed. Now think what a world-astounding collaboration we should be, you and I - together.
Henry: No! No, no, no.

The unforgettable weirdo scientist insists that Frankenstein work with him, but Henry soundly refuses Pretorius' offer to make real their creative sexual fantasies through collaboration, thinking the man is profoundly mad and power-crazy. Pretorius coyly urges further that they produce another full-sized human to tempt the first male [Adam symbolically] of their artificially-created race with a mate - a second female creation [Eve symbolically], giving rise to heterosexuality. In his own version of the Garden of Eden story, Pretorius becomes deified and God-like, while presenting evidence of his skepticism with religion. He also entices Henry away from marriage and the creation of life (with a real woman) by proposing the unholy idea of creating their own race of "Gods and Monsters":

Pretorius: Leave the charnel house and follow the lead of Nature - or of God if you like your Bible stories. (suggestively) Male and Female created He them. Be fruitful and multiply. Create a race, a man-made race upon the face of the earth. Why not?
Henry: (agitated and alarmed) I daren't. I daren't even think of such a thing.
Pretorius: Our mad dream is only half realized. Alone, you have created a man. Now together, we will create his mate.
Henry (sitting forward): You mean...?
Pretorius: (lasciviously) Yes. A woman. That should be really interesting. (The screen turns black after his degenerate comment.)

Interesting indeed to create a "mate," since Pretorius hasn't yet learned that the Monster is still alive.

Meanwhile, the Monster stomps through an Expressionistic, sunlit woods with thick underbrush. He finds a still, placid pool and scoops up water to quench his thirst. His hideous reflection bothers him, and he angrily growls and strikes the water's surface to erase away his ugly image. Contented sheep are being tended by a beautiful young shepherdess (Ann Darling). Seeking friendship, the Monster staggers over to her. When she sights him, she screams, loses her balance on the rock cliff, and plummets into the pool. He follows her into the water and saves her life. [Following his experience in the first film with Maria, the Monster knows he must save the girl from drowning!] Spurning him, her terrified screams alert nearby hunters who attack him. For his magnanimity, he is shot in the arm and chased through the forest. One of the hunters notifies the burgomaster and other villagers that the Monster is on a rampage, and a search is immediately organized: "Get out the bloodhounds. Raise all the men you can, lock the women indoors, and wait for me."

The Monster is pursued uphill in the same forest (now a stark woods filled with bare trunks of trees and rocky outcroppings and lacking dense undergrowth) by angry, blood-thirsty townspeople and bloodhounds barking after their prey. After pushing a rock boulder down on two of the villagers, the Monster is surrounded by the irate mob. Minnie is present at the moment of the capture and sharply exclaims to the burgomaster: "Mind me he don't get loose again. He might do some damage and hurt somebody." In an image heavy with Christian religious symbolism, the captured Monster is lashed to a long wooden pole, raised and hung up - and placed in a suffering, crucifixion pose, as the villagers revile him and stone him with rocks. He is taken into town in a haycart, carried on the long pole like a captured boar into an old underground dungeon, and painfully chained (around the neck) and shackled into a stone throne-chair. The Monster is jeered at through a window by the townspeople, and Minnie gawks at the imprisoned creature: "I'd hate to find him under my bed at night. He's a nightmare in the daylight, he is."

With his brute, superhuman strength, the Monster quickly breaks from his chains, kills one of the guards and escapes into the street. As the burgomaster calmly assures the townsfolk that the Monster is "quite harmless," the murderous creature appears, causing an hysterical panic. Before running, cowardly Minnie intimidates one of the men to defend himself: "Why don't you shoot him?" - the man gets his head bashed into the ground. A virginal young girl in a white outfit is killed in the murder spree. Minnie discovers other Monster victims - the Neumanns.

The Monster returns to the woods that evening, where he hungrily smells a chicken roasting above a gypsy campfire. He assaults the terrorized family around the fire and burns his hand reaching to snatch the food. Wandering and blundering around some more, he finally seeks idyllic refuge at the cabin of an old blind hermit (O. P. Heggie), when he is attracted to the sad violin strains of the man's instrument playing Ave Maria. Approaching with a smile and a friendly demeanor, the mute Monster stumbles into the blind man's home and is welcomed: "Who is it? You're welcome, my friend, whoever you are." Hospitable to his stray-dog visitor, the pure-of-heart blind hermit befriends the disturbed creature, becoming his first supportive friend:

Come in, my poor friend. No one will hurt you here. If you're in trouble, perhaps I can help you. But you need not tell me about it if you don't want to. What's the matter? (The blind man feels and discovers the Monster's wounded hand.) You're hurt, my poor friend. Come. Sit down.

The hermit realizes that they both have crippling disabilities: "Perhaps you're afflicted too. I cannot see and you cannot speak. Is that it?" The Monster gestures affirmatively. The hermit feeds his friend and treats the creature with great kindness, tenderness and respect. Thinking he has finally been sent a friend (another "lonely child(ren)") from God, the lonely man is overjoyed and thanks God for the answer to his prayers. Maudlin church organ music on the soundtrack (playing the same Ave Maria) accompanies his prayer:

I have prayed many times for God to send me a friend. It's very lonely here. And it's been a long time since any human being came into this hut. I shall look after you and you will comfort me. Now you must lie down and go to sleep. Yes, yes. Now you must sleep. (He takes the Monster's hand) Our Father I thank thee that in thy great mercy, thou hast taken pity on my great loneliness and now out of the silence of the night has brought two of thy lonely children together, and sent me a friend to be a light to mine eyes and a comfort in time of trouble. Amen.

In the incredible scene, the Monster sees the hermit break down and cry at the end of the prayer. The child-like Monster sheds a tear and compassionately reaches out to comfort the crying man with a consoling pat on the back. They both share a need for human compassion. A Christian crucifix prominently hangs on the wall above the Monster. During the prolonged fadeout from the scene, the glowing crucifix is the last object to vanish from view.

Later, the hermit teaches the Monster a rudimentary vocabulary of simple words (both concrete and abstract words) while introducing the creature to simple pleasures - food, smoke, and music. The Monster pronounces the words in gutteral tones - "Bread" and "Wine" [the traditional elements of the Sacrament], "Drink," "Good," and "Friends." Although fearful of the fiery match used to light a cigar, the Monster is encouraged to learn how to smoke - with child-like pleasure, he puffs away, exclaiming: "Good, good." The hermit is pleased with his companion: "Before you came, I was all alone. It is bad to be alone." Two more words are added to the growing vocabulary: "Alone" and "Bad." ("Alone: bad. Friend: good! Friend: good! Ha, ha, ha.") The Monster is taught that one adds "Wood" to the "Fire," although he strongly disagrees with the hermit: "Fire - No Good." The hermit is encouraged to play his violin by the music-loving Monster and the two quickly forget their loneliness in their little Utopia. The Monster sits at his teacher's feet, smoking and listening to the violin music.

The same two hunters who shot at the Monster earlier lose their way in the forest - they intrude upon their safe and peaceful world and knock at the door, discovering the Monster's whereabouts. Panicked, they gasp: "Look, it's the Monster!" Abruptly, the Monster rises ominously and growls, his face growing cold and menacing. He throws down one of the threatening hunters as the hermit defends his Monster friend: "What are you doing? This is my friend!" In an ironic question, the hermit learns the Monster's true identity from one of the astonished hunters: "Friend?! This is the fiend that's been murdering half the countryside. Good heavens, man, can't you see?...He isn't human. Frankenstein made him out of dead bodies."

In a struggle, the hut is accidentally set on fire and while the Monster cowers inside as the flames expand, the bewildered, protesting hermit is removed and led away from the hut by the hunters. The Monster eventually stumbles through the smoke to the door, holds out his hands and pleadingly cries: "Friend?" but there is no answer.

Miserable and on the run again, the Monster enters a surrealistic graveyard - a return to his origins among the dead - and another crucifix figure. He pushes over a dead tree trunk and angrily desecrates a religious statue of a Catholic bishop by knocking it over. In front of another large, stark crucifix, he steps down into an underground crypt to hide from torch-carrying villagers. As he turns and descends into the entrance of the tomb, his image and form resemble the crucifix behind him. In the mausoleum, he speaks lovingly (and with necrophiliac overtones) to the corpse of a deceased girl in a coffin, calling it: "Friend."